Method of measuring level in a vessel

A method of measuring level in a vessel by means of a level measuring device operating with pulses, said method compring the steps of:

• coupling waves to be transmitted into the vessel and receiving echo waves reflected from the contents of the vessel;
• generating an envelope signal representative of transmitted waves and echo waves with at least one echo pulse;
• generating a digital sampling sequence from the envelope signal;
• generating a first data tuple, representative of a reference point in said envelope signal;
• generating a second data tuple, representative of an echo pulse in said envelope signal, by means of the sampling sequence, each of said first and second data tupel having an amplitude value and a transit time value;
• and
• deriving from the envelope signal a measured value representative of the level of the contents, this step comprising a step of determining a difference between the transit time value of the first data tuple and the transit time value of the second data tuple,
• wherein the step of generating the second data tuple further comprises the steps of:
• determining a first data record of the sampling sequence, said first data record being representative of a local extremum of the sampling sequence and having a transit time value greater than that of the first data tuple;
• determining at least a second data record of the sampling sequence having a transit time value greater than that of the first data tuple and less than that of the first data record;
• determining at least a third data record of the sampling sequence having a transit time value greater than that of the first data record;
• deriving from the digital sampling sequence an extreme value representative of a highest amplitude value of the echo pulse by means of the first, second, and third data records;
• and
• determining the transit time value of the second data tuple by means of said extreme value.